This invention relates to a boiler installation for the combustion of solid fuels, for example forest waste material in the form of e.g. bark and/or chips, peat pellets, coal etc., comprising a fire box located in connection to a heat medium portion and in said fire box a grate means. The grate means advances fuel through a fuel charge opening through the fire box while the fuel is being combusted, from which fire box the flue gases flow to the heat medium portion and continue to a chimney. The boiler includes at least one intake for adjustable supply of combustion air in the form of at least primary and secondary combustion air.
The utilization of forest waste material and other biologic material as fuel has increased, in spite of the absence of efficient boiler installations, which with high efficiency degree, due to great variations of the continuous load are capable to combust such forest waste material. The material possesses such disadvantages as for example highly varying quality and varying moisture content and a moisture content often amounting to 70% and even higher.
An object of the present invention, therefore, is to bring about such a boiler installation, which renders it possible to combust with high efficiency degree and completely forest waste material and other biologic fuels, which may have a high moisture content, without requiring these fuels first to be dried. The installation, besides, shall be manufactured and mounted in a simple way. These objects and others are achieved by the boiler installation according to the present invention.